1. Field of the Invention
The present invention is related to dipstick assemblies and, more particularly, is directed towards a novel combination of a dipstick and plug for an oil filler tube of an engine.
2. Description of the Prior Art
Several United States patents are known to us which broadly disclose dipstick and plug assemblies adapted to be inserted within an oil filler tube of an engine. These include: U.S. Pat. Nos. 2,343,168; 3,269,703; 3,371,418; and 3,626,596.
The first-named patent to Bickle (U.S. Pat. No. 2,343,168) sets forth a dipstick gauge which includes a dipstick to one end of which is connected a handle and having a stop collar formed intermediate the handle and the gauge.
U.S. Pat. No. 3,296,703 to Stade et al sets forth a dipstick have a finger ring serving as a handle. Two pair of disc washers are secured about the blade of the dipstick below the handle and serve to hold a pair of O-rings. The O-rings, in turn, provide a fluid-tight connection in the bore of the oil filler tube.
The Moeller U.S. Pat. No. 3,371,418 sets forth a dipstick assembly which features a closure means for the oil filler tube that comprises a resilient compressible body with peripheral sealing ribs formed thereabout.
U.S. Pat. No. 3,625,596 to Manke teaches a dipstick and plug assembly wherein a cylindrical plug includes a plurality of specially shaped projections formed peripherally thereabout which contact the inner surface of the oil filler tube. The dipstick is embedded within the shank of the plug, the latter also including an integrally formed handle.
While the prior art patents discussed above illustrate the progression of this art through the years, presently available dipstick and plug assemblies nevertheless continue to suffer from several deficiencies. Initially, it may be noted that the prior art assemblies are far too complex to be produced cheaply and efficiently, which results in an undesirably expensive item being provided to the consumer.
Secondly, the prior art devices, while purporting to perform the two distinct functions required of them, i.e., both sealing the filler tube against outside dirt and contamination, and holding the dipstick in place within the tube, generally fail to perform both functions with equal proficiency. Some of the designs, for example, while providing an efficient seal, tend to "walk out" of the filler tube as a result of normal vibrations encountered during engine operation. This is believed due to the provision of overly flexible sealing means. Other designs attempt to overcome this problem by providing integrally formed relatively rigid ribs about the periphery of the plug. However, as evidenced by the Manke patent, such ribs must be formed in a special shape to prevent undue binding of the plug in the oil filler tube during insertion and withdrawal. Such special shapes tend to increase production costs unduly, to the ultimate detriment of the consumer.